Frequency hopping in ofdma wireless networks

ABSTRACT

Method and systems are disclosed for qualifying a wireless device as frequency hopping device. In some aspects, an access point (AP) may determine a frequency hopping pattern for the wireless device, and then allocate a sequence of unique resource units to the wireless device based on the frequency hopping pattern. Each of the unique resource units include a different set of frequency subcarriers. The AP may receive a series of uplink orthogonal frequency-division multiple access (OFDMA) transmissions from the wireless device on the allocated sequence of unique resource units.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority to U.S. Provisional PatentApplication No. 62/321,930 filed on Apr. 13, 2016 entitled FREQUENCYHOPPING IN OFDMA WIRELESS NETWORKS,” assigned to the assignee hereof.The disclosure of the prior application is considered part of and isincorporated by reference in this patent application.

TECHNICAL FIELD

This disclosure relates generally to wireless networks, and specificallyto employing frequency hopping techniques in wireless local areanetworks.

DESCRIPTION OF THE RELATED TECHNOLOGY

A wireless local area network (WLAN) may be formed by one or more accesspoints (APs) that provide a shared wireless medium for use by a numberof wireless devices or stations (STAs). Each AP, which may correspond toa Basic Service Set (BSS), periodically broadcasts beacon frames toenable any STAs within wireless range of the AP to establish andmaintain a communication link with the WLAN. Wireless networks thatoperate in accordance with the IEEE 802.11 family of standards may bereferred to as Wi-Fi networks, and wireless devices that transmitsignals according to communication protocols specified by the IEEE802.11 family of standards may be referred to as Wi-Fi devices.

The wireless range of a Wi-Fi device may be related to its transmissionpower level. For example, wireless signals transmitted at higher powerlevels typically travel farther than wireless signals transmitted atlower power levels. Many governmental regulations impose a powerspectral density limit on the transmission power of wireless devices.These power spectral density limits may undesirably limit the range ofWi-Fi devices.

SUMMARY

The systems, methods and devices of this disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

One innovative aspect of the subject matter described in this disclosurecan be implemented in a Wi-Fi network to increase the wireless range ofWi-Fi devices without violating power spectral density limits imposed bygovernmental regulations. In some implementations, a wireless device mayemploy frequency hopping techniques during OFDMA transmissions toqualify as a frequency hopping device. Because many governmentalregulations impose less stringent power spectral density limits onfrequency hopping devices than on Wi-Fi devices, qualifying the wirelessdevice as a frequency hopping device during OFDMA transmissions mayallow the wireless device to transmit data at the higher power levelsassociated with frequency hopping devices. In this manner, aspects ofthe present disclosure may increase the wireless range of Wi-Fi deviceswithout violating power spectral density limits imposed by governmentalregulations.

In some implementations, an access point (AP) can include one or moreprocessors and a memory storing instructions. The instructions can beexecuted by the one or more processors to cause the AP to qualify awireless device as frequency hopping device by determining a frequencyhopping pattern for the wireless device; allocating a sequence of uniqueresource units to the wireless device based on the frequency hoppingpattern, each of the unique resource units including a different set offrequency subcarriers; and receiving, from the wireless device, a seriesof uplink orthogonal frequency-division multiple access (OFDMA)transmissions on the allocated sequence of unique resource units duringa sequence period.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented as a method for qualifying a wirelessdevice as frequency hopping device. The method can include determining afrequency hopping pattern for the wireless device; allocating a sequenceof unique resource units to the wireless device based on the frequencyhopping pattern, each of the unique resource units including a differentset of frequency subcarriers; and receiving, from the wireless device, aseries of uplink orthogonal frequency-division multiple access (OFDMA)transmissions on the allocated sequence of unique resource units duringa sequence period.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a non-transitory computer-readablemedium. The non-transitory computer-readable medium can compriseinstructions that, when executed by one or more processors of an AP,cause the AP to qualify a wireless device as frequency hopping device byperforming operations that include determining a frequency hoppingpattern for the wireless device; allocating a sequence of uniqueresource units to the wireless device based on the frequency hoppingpattern, each of the unique resource units including a different set offrequency subcarriers; and receiving, from the wireless device, a seriesof uplink orthogonal frequency-division multiple access (OFDMA)transmissions on the allocated sequence of unique resource units duringa sequence period.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in an apparatus. The apparatus can includemeans for determining a frequency hopping pattern for the wirelessdevice; means for allocating a sequence of unique resource units to thewireless device based on a frequency hopping pattern, each of the uniqueresource units including a different set of frequency subcarriers; andmeans for receiving, from the wireless device, a series of uplinkorthogonal frequency-division multiple access (OFDMA) transmissions onthe allocated sequence of unique resource units during a sequenceperiod.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a wireless station. The wirelessstation can include one or more processors and a memory. The memory canstore instructions that, when executed by the one or more processors,cause the wireless station to qualify as a frequency hopping device by:receiving a frequency hopping pattern; receiving an allocation of asequence of unique resource units based on the frequency hoppingpattern, each of the unique resource units including a different set offrequency subcarriers; and transmitting a series of orthogonalfrequency-division multiple access (OFDMA) data transmissions on theallocated sequence of unique resource units during a sequence period. Insome aspects, the wireless station can receive a trigger frame thatallocates the sequence of unique resource units to the wireless stationand indicates that the wireless station is to successively frequency hopbetween more than a specified number of the unique resource units. Thetrigger frame also may contain one of an indication that the wirelessstation is to dwell on each of the unique resource units for less than aduration and an indication that an accumulated dwell time in the uniqueresource units is to be no more than a time period greater than aduration of the sequence of unique resource units.

Details of one or more implementations of the subject matter describedin this disclosure are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of an example wireless system.

FIG. 2 shows a block diagram of an example wireless station.

FIG. 3 shows a block diagram of an example access point.

FIG. 4 shows an example subcarrier allocation diagram for narrowbandtransmissions.

FIG. 5 shows a sequence diagram depicting an example allocation ofresource units for uplink transmissions.

FIG. 6A shows a sequence diagram depicting an example allocation ofresource units based on frequency hopping.

FIG. 6B shows a sequence diagram depicting another example allocation ofresource units based on frequency hopping.

FIG. 7A shows an illustration depicting example sequences of resourceunits that may be used for frequency hopping during OFDMA transmissions.

FIG. 7B shows an illustrative table depicting an example construction ofone of the resource unit sequences of FIG. 7A.

FIG. 8 shows an example trigger frame.

FIG. 9A shows an example Common Info field.

FIG. 9B shows an example Per User Info field.

FIG. 10 shows an illustrative flow chart depicting an example operationfor qualifying a wireless device as frequency hopping device.

FIG. 11 shows an illustrative flow chart depicting an example operationfor allocating resource units to a wireless device.

FIG. 12 shows an illustrative flow chart depicting an example operationfor a wireless station transmitting data using resource units allocatedbased on a frequency hopping schedule.

Like reference numerals refer to corresponding parts throughout thedrawing figures.

DETAILED DESCRIPTION

The following description is directed to certain implementations for thepurposes of describing the innovative aspects of this disclosure.However, a person having ordinary skill in the art will readilyrecognize that the teachings herein can be applied in a multitude ofdifferent ways. The described implementations may be implemented in anydevice, system or network that is capable of transmitting and receivingRF signals according to any of the IEEE 16.11 standards, or any of theIEEE 802.11 standards, the Bluetooth® standard, code division multipleaccess (CDMA), frequency division multiple access (FDMA), time divisionmultiple access (TDMA), Global System for Mobile communications (GSM),GSM/General Packet Radio Service (GPRS), Enhanced Data GSM Environment(EDGE), Terrestrial Trunked Radio (TETRA), Wideband-CDMA (W-CDMA),Evolution Data Optimized (EV-DO), 1×EV-DO, EV-DO Rev A, EV-DO Rev B,High Speed Packet Access (HSPA), High Speed Downlink Packet Access(HSDPA), High Speed Uplink Packet Access (HSUPA), Evolved High SpeedPacket Access (HSPA+), Long Term Evolution (LTE), AMPS, or other knownsignals that are used to communicate within a wireless, cellular orinternet of things (IOT) network, such as a system utilizing 3G, 4G or5G, or further implementations thereof, technology.

The range of a wireless device may be based at least in part on itstransmission power and transmission bandwidth. For example, wirelesssignals transmitted at higher power levels typically travel farther thanwireless signals transmitted at lower power levels, and wireless signalstransmitted using a relatively wide bandwidth typically travel fartherthan wireless signals transmitted using a relatively narrow bandwidth.Governmental regulations that impose power spectral density limits onthe transmission power of wireless devices may undesirably limit therange of wireless devices. In many regions of the world, the powerspectral density limits imposed on frequency hopping devices are lessstringent than the power spectral density limits imposed on Wi-Fidevices. For example, the European Telecommunications StandardsInstitute (ETSI) imposes a 14 dBm power limit on Wi-Fi devices thattransmit data on a 2 MHz resource unit (RU) using orthogonalfrequency-division multiple access (OFDMA) communications, and imposes a20 dBm power limit on frequency hopping devices that transmit data on a2 MHz channel In other words, while a frequency hopping device maytransmit data using a 2 MHz bandwidth at power levels up to 20 dBm, aWi-Fi device transmitting data using a 2 MHz bandwidth is limited 14dBm.

Implementations of the subject matter described in this disclosure mayallow a Wi-Fi device to transmit wireless signals at higher power levelsby qualifying the Wi-Fi device as a frequency hopping device. Morespecifically, in accordance with aspects of the present disclosure, aWi-Fi device can qualify as a frequency hopping device by usingfrequency hopping techniques during OFDMA transmissions. In someimplementations, an access point (AP) can determine a frequency hoppingschedule that is compliant with applicable power spectral density limitsimposed on frequency hopping devices, and then announce or otherwiseindicate the determined frequency hopping schedule to a number of Wi-Fidevices associated with the AP. The AP also can allocate resource units(RUs) to the number of Wi-Fi devices for uplink (UL) data transmissionsbased on the determined frequency hopping schedule. The Wi-Fi devicescan receive the determined frequency hopping schedule and the allocationof RUs, and thereafter transmit UL data based on the determinedfrequency hopping schedule and the allocated RUs.

As used herein, the term “associated AP” refers to an AP with which agiven STA is associated (such as there is an established communicationchannel or link between the AP and the given STA). The term“non-associated AP” refers to an AP with which a given STA is notassociated (such as there is not an established communication channel orlink between the AP and the given STA, and thus the AP and the given STAmay not yet exchange data frames). The term “associated STA” refers to aSTA that is associated with a given AP, and the term “non-associatedSTA” refers to a STA that is not associated with the given AP.Additionally, the term “narrowband” may refer to a bandwidth that isless than 20 MHz (such as a 2 MHz bandwidth, a 4 MHz bandwidth, an 8 MHzbandwidth, and a 16 MHz bandwidth), and the term “wideband” may refer toa bandwidth that is greater than or equal to 20 MHz (such as a primary20 MHz channel, a secondary 20 MHz channel, a secondary 40 MHz channel,a secondary 80 MHz channel, and so on).

FIG. 1 shows a block diagram of an example wireless system 100. Thewireless system 100 is shown to include four wireless stationsSTA1-STA4, a wireless access point (AP) 110, and a wireless local areanetwork (WLAN) 120. The WLAN 120 may be formed by a plurality of Wi-Fiaccess points (APs) that may operate according to the IEEE 802.11 familyof standards (or according to other suitable wireless protocols). Thus,although only one AP 110 is shown in FIG. 1 for simplicity, it is to beunderstood that the WLAN 120 may be formed by any number of accesspoints such as the AP 110. The AP 110 is assigned a unique MAC addressthat is programmed therein by, for example, the manufacturer of theaccess point. Similarly, each of the stations STA1-STA4 is also assigneda unique MAC address. In some aspects, the AP 110 may assign anassociation identification (AID) value to each of the stationsSTA1-STA4, for example, so that the AP 110 may identify the stationsSTA1-STA4 using their assigned AID values.

In some implementations, the WLAN 120 may allow for multiple-inputmultiple-output (MIMO) communications between the AP 110 and thestations STA1-STA4. The MIMO communications may include single-user MIMO(SU-MIMO) and multi-user MIMO (MU-MIMO) communications. In some aspects,the WLAN 120 may utilize a multiple channel access mechanism such as,for example, an orthogonal frequency-division multiple access (OFDMA)mechanism. Although the WLAN 120 is depicted in FIG. 1 as aninfrastructure basic service set (BSS), in other implementations, theWLAN 120 may be an independent basic service set (IBSS), an ad-hocnetwork, or a peer-to-peer (P2P) network (such as operating according tothe Wi-Fi Direct protocols).

Each of the stations STA1-STA4 may be any suitable wireless deviceincluding, for example, a cell phone, personal digital assistant (PDA),tablet device, laptop computer, or the like. Each of the stationsSTA1-STA4 may also be referred to as a user equipment (UE), a subscriberstation, a mobile unit, a subscriber unit, a wireless unit, a remoteunit, a mobile device, a wireless device, a wireless communicationsdevice, a remote device, a mobile subscriber station, an accessterminal, a mobile terminal, a wireless terminal, a remote terminal, ahandset, a user agent, a mobile client, a client, or some other suitableterminology. In some implementations, each of the stations STA1-STA4 mayinclude one or more transceivers, one or more processing resources, oneor more memory resources, and a power source (such as a battery). Thememory resources may include a non-transitory computer-readable medium(such as one or more nonvolatile memory elements, such as EPROM, EEPROM,Flash memory, a hard drive, etc.) that stores instructions forperforming operations described below with respect to FIGS. 10-12.

The AP 110 may be any suitable device that allows one or more wirelessdevices to connect to a network (such as a local area network (LAN),wide area network (WAN), metropolitan area network (MAN), or theInternet) via the AP 110 using wireless communications such as, forexample, Wi-Fi, Bluetooth, and cellular communications. In someimplementations, the AP 110 may include one or more transceivers, one ormore processing resources, one or more memory resources, and a powersource. The memory resources may include a non-transitorycomputer-readable medium (such as one or more nonvolatile memoryelements, such as EPROM, EEPROM, Flash memory, a hard drive, etc.) thatstores instructions for performing operations described below withrespect to FIGS. 10-12.

For the stations STA1-STA4 and the AP 110, the one or more transceiversmay include Wi-Fi transceivers, Bluetooth transceivers, cellulartransceivers, and any other suitable radio frequency (RF) transceivers(not shown for simplicity) to transmit and receive wirelesscommunication signals. Each transceiver may communicate with otherwireless devices in distinct operating frequency bands, using distinctcommunication protocols, or both. For example, the Wi-Fi transceiver maycommunicate within a 900 MHz frequency band, a 2.4 GHz frequency band, a5 GHz frequency band, and a 60 MHz frequency band in accordance with theIEEE 802.11 standards. The Bluetooth transceiver may communicate withinthe 2.4 GHz frequency band in accordance with the standards provided bythe Bluetooth Special Interest Group (SIG), in accordance with the IEEE802.15 standards, or both. The cellular transceiver may communicatewithin various RF frequency bands in accordance with any suitablecellular communications standard.

FIG. 2 shows a block diagram of an example wireless station (STA) 200.In some implementations, the STA 200 may be one example of one or moreof the wireless stations STA1-STA4 of FIG. 1. The STA 200 may include adisplay 202, input/output (I/O) components 204, a physical-layer device(PHY) 210, a MAC 220, a processor 230, a memory 240, and a number ofantennas 250(1)-250(n). The display 202 may be any suitable display orscreen upon which items may be presented to a user (such as for viewing,reading, or watching). In some aspects, the display 202 may be atouch-sensitive display that allows for user interaction with the STA200 and that allows the user to control one or more operations of theSTA 200. The I/O components 204 may be or include any suitablemechanism, interface, or device to receive input (such as commands) fromthe user and to provide output to the user. For example, the I/Ocomponents 204 may include (but are not limited to) a graphical userinterface, keyboard, mouse, microphone, speakers, and so on.

The PHY 210 may include at least a number of transceivers 211 and abaseband processor 212. The transceivers 211 may be coupled to theantennas 250(1)-250(n), either directly or through an antenna selectioncircuit (not shown for simplicity). The transceivers 211 may be used totransmit signals to and receive signals from the AP 110 and other STAs(see also FIG. 1), and may be used to scan the surrounding environmentto detect and identify nearby access points and other STAs (such aswithin wireless range of the STA 200). Although not shown in FIG. 2 forsimplicity, the transceivers 211 may include any number of transmitchains to process and transmit signals to other wireless devices via theantennas 250(1)-250(n), and may include any number of receive chains toprocess signals received from the antennas 250(1)-250(n). In someimplementations, the STA 200 may be configured for MIMO operations. TheMIMO operations may include SU-MIMO operations and MU-MIMO operations.The STA 200 also may be configured for OFDMA communications and othersuitable multiple access mechanisms, for example, as may be provided bythe IEEE 802.11ax specification.

The baseband processor 212 may be used to process signals received fromthe processor 230 or the memory 240 (or both) and to forward theprocessed signals to the transceivers 211 for transmission via one ormore of the antennas 250(1)-250(n). The baseband processor 212 also maybe used to process signals received from one or more of the antennas250(1)-250(n) via the transceivers 211 and to forward the processedsignals to the processor 230 or the memory 240 (or both).

The MAC 220 may include at least a number of contention engines 221 andframe formatting circuitry 222. The contention engines 221 may contendfor access to a shared wireless medium (or contend for access to one ormore resource units), and also may store packets for transmission overthe shared wireless medium (such as using one or more resource units).The STA 200 may include one or more contention engines 221 for each of aplurality of different access categories. In other implementations, thecontention engines 221 may be separate from the MAC 220. For still otherimplementations, the contention engines 221 may be implemented as one ormore software modules (such as stored in the memory 240 or stored in amemory provided within the MAC 220) containing instructions that, whenexecuted by the processor 230, perform the functions of the contentionengines 221.

The frame formatting circuitry 222 may be used to create and formatframes received from the processor 230 (such as by adding MAC headers toPDUs provided by the processor 230), and may be used to re-format framesreceived from the PHY 210 (such as by stripping MAC headers from framesreceived from the PHY 210). Although the example of FIG. 2 depicts theMAC 220 coupled to the memory 240 via the processor 230, in otherimplementations, the PHY 210, the MAC 220, the processor 230, and thememory 240 may be connected using one or more buses (not shown forsimplicity).

The processor 230 may be any suitable one or more processors capable ofexecuting scripts or instructions of one or more software programsstored in the STA 200 (such as within the memory 240). In someimplementations, the processor 230 may be or include one or moremicroprocessors providing the processor functionality and externalmemory providing at least a portion of machine-readable media. In otherimplementations, the processor 230 may be or include an ApplicationSpecific Integrated Circuit (ASIC) with the processor, the businterface, the user interface, and at least a portion of themachine-readable media integrated into a single chip. In some otherimplementations, the processor 230 may be or include one or more FieldProgrammable Gate Arrays (FPGAs) or Programmable Logic Devices (PLDs).

The memory 240 may include a device database 241 that stores profileinformation for the STA 200 and for a number of other wireless devices(such as APs and other STAs). The profile information for the STA 200may include, for example, its MAC address, the basic service setidentification (BSSID) of the basic service set to which the STA 200belongs, its bandwidth capabilities, its supported channel accessmechanisms, its supported data rates, and so on. The profile informationfor a particular AP may include, for example, the AP's BSSID, MACaddress, channel information, frequency hopping schedule, receivedsignal strength indicator (RSSI) values, goodput values, channel stateinformation (CSI), supported data rates, connection history with the STA200, a trustworthiness value of the AP (such as indicating a level ofconfidence about the AP's location, etc.), and any other suitableinformation pertaining to or describing the operation of the AP.

The memory 240 also may include a frequency hopping database 242. Thefrequency hopping database 242 may store one or more frequency hoppingpatterns, a frequency hopping schedule (such as provided by an AP), oneor more sequences of resource units (such as allocated based on thefrequency hopping schedule), a maximum resource unit dwell time, anaccumulated sequence period dwell time, or any other suitableinformation pertaining to or describing frequency hopping techniquesemployed by the STA 200.

The memory 240 may also include a non-transitory computer-readablemedium (such as one or more nonvolatile memory elements, such as EPROM,EEPROM, Flash memory, a hard drive, and so on) that may store at leastthe following software (SW) modules:

-   -   a frame formatting and exchange software module 243 to        facilitate the creation and exchange of any suitable frames        (such as data frames, action frames, control frames, and        management frames) between the STA 200 and other wireless        devices, for example, as described below for one or more        operations of FIGS. 10-12;    -   a trigger frame reception software module 244 to receive trigger        frames, to determine whether the trigger frames allocate        resource units (RUs) to the STA 200, and to determine whether        the trigger frames indicate a frequency hopping schedule, for        example, as described below for one or more operations of FIGS.        10-12; and    -   a resource unit and frequency hopping decoding software module        245 to determine which (if any) RUs are allocated to the STA        200, and to decode frequency hopping schedules and RU sequences        for the STA 200, for example, as described below for one or more        operations of FIGS. 10-12.        Each software module includes instructions that, when executed        by the processor 230, cause the STA 200 to perform the        corresponding functions. The non-transitory computer-readable        medium of the memory 240 thus includes instructions for        performing all or a portion of the operations described below        with respect to FIGS. 10-12.

The processor 230 may execute the frame formatting and exchange softwaremodule 243 to facilitate the creation and exchange of any suitableframes (such as data frames, action frames, control frames, andmanagement frames) between the STA 200 and other wireless devices. Theprocessor may execute the trigger frame reception software module 244 toreceive trigger frames, to determine whether the trigger frames allocateresource units (RUs) to the STA 200, and to determine whether thetrigger frames indicate a frequency hopping schedule. The processor mayexecute the resource unit and frequency hopping decoding software module245 to determine which (if any) RUs are allocated to the STA 200, and todecode frequency hopping schedules and RU sequences for the STA 200.

FIG. 3 shows a block diagram of an example access point (AP) 300. Insome implementations, the AP 300 may be one example of the AP 110 ofFIG. 1. The AP 300 may include a PHY 310, a MAC 320, a processor 330, amemory 340, a network interface 350, and a number of antennas360(1)-360(n). The PHY 310 may include at least a number of transceivers311 and a baseband processor 312. The transceivers 311 may be coupled tothe antennas 360(1)-360(n), either directly or through an antennaselection circuit (not shown for simplicity). The transceivers 311 maybe used to communicate wirelessly with one or more STAs, with one ormore other APs, and with other suitable devices. Although not shown inFIG. 3 for simplicity, the transceivers 311 may include any number oftransmit chains to process and transmit signals to other wirelessdevices via the antennas 360(1)-360(n), and may include any number ofreceive chains to process signals received from the antennas360(1)-360(n). In some implementations, the AP 300 may be configured forMIMO operations such as SU-MIMO operations and MU-MIMO operations. TheAP 300 also may be configured for OFDMA communications and othersuitable multiple access mechanisms, for example, as may be provided bythe IEEE 802.11ax specification.

The baseband processor 312 may be used to process signals received fromthe processor 330 or the memory 340 (or both) and to forward theprocessed signals to the transceivers 311 for transmission via one ormore of the antennas 360(1)-360(n). The baseband processor 312 also maybe used to process signals received from one or more of the antennas360(1)-360(n) via the transceivers 311 and to forward the processedsignals to the processor 330 or the memory 340 (or both).

The network interface 350 may be used to communicate with a WLAN server(not shown for simplicity) either directly or via one or moreintervening networks and to transmit signals.

The MAC 320 may include at least a number of contention engines 321 andframe formatting circuitry 322. The contention engines 321 may contendfor access to the shared wireless medium, and also may store packets fortransmission over the shared wireless medium. In some implementations,the AP 300 may include one or more contention engines 321 for each of aplurality of different access categories. In other implementations, thecontention engines 321 may be separate from the MAC 320. For still otherimplementations, the contention engines 321 may be implemented as one ormore software modules (such as stored in the memory 340 or within amemory provided within the MAC 320) containing instructions that, whenexecuted by the processor 330, perform the functions of the contentionengines 321.

The frame formatting circuitry 322 may be used to create and formatframes received from the processor 330 (such as by adding MAC headers toPDUs provided by the processor 330), and may be used to re-format framesreceived from the PHY 310 (such as by stripping MAC headers from framesreceived from the PHY 310). Although the example of FIG. 3 depicts theMAC 320 coupled to the memory 340 via the processor 330, in otherimplementations, the PHY 310, the MAC 320, the processor 330, and thememory 340 may be connected using one or more buses (not shown forsimplicity).

The processor 330 may be any suitable one or more processors capable ofexecuting scripts or instructions of one or more software programsstored in the AP 300 (such as within the memory 340). In someimplementations, the processor 330 may be or include one or moremicroprocessors providing the processor functionality and externalmemory providing at least a portion of machine-readable media. In otherimplementations, the processor 330 may be or include an ApplicationSpecific Integrated Circuit (ASIC) with the processor, the businterface, the user interface, and at least a portion of themachine-readable media integrated into a single chip. In some otherimplementations, the processor 330 may be or include one or more FieldProgrammable Gate Arrays (FPGAs) or Programmable Logic Devices (PLDs).

The memory 340 may include a device database 341 that stores profileinformation for a plurality of STAs. The profile information for aparticular STA may include, for example, its MAC address, supported datarates, connection history with the AP 300, one or more RUs allocated tothe STA, a frequency hopping pattern of the STA, one or more RUsequences allocated to the STA, and any other suitable informationpertaining to or describing the operation of the STA.

The memory 340 also may include a non-transitory computer-readablemedium (such as one or more nonvolatile memory elements, such as EPROM,EEPROM, Flash memory, a hard drive, and so on) that may store at leastthe following software (SW) modules:

-   -   a frame formatting and exchange software module 342 to        facilitate the creation and exchange of any suitable frames        (such as data frames, action frames, control frames, and        management frames) between the AP 300 and other wireless        devices, for example, as described below for one or more        operations of FIGS. 10-12;    -   a frequency hopping pattern and scheduling SW module 343 to        select a unique frequency hopping pattern for each of a number        of wireless devices and to determine or select a frequency        hopping schedule based on the unique frequency hopping patterns,        for example, as described below for one or more operations of        FIGS. 10-12;    -   a resource unit (RU) allocation software module 344 to allocate        unique sequences of RUs to the wireless devices (such as based        on frequency hopping schedules or unique frequency hopping        patterns), for example, as described below for one or more        operations of FIGS. 10-12; and    -   an announcement software module 345 to announce or otherwise        indicate the frequency hopping patterns, the frequency hopping        schedule, and the allocation of unique sequences of RUs to the        wireless devices, for example, as described below for one or        more operations of FIGS. 10-12.        Each software module includes instructions that, when executed        by the processor 330, cause the AP 300 to perform the        corresponding functions. The non-transitory computer-readable        medium of the memory 340 thus includes instructions for        performing all or a portion of the operations described below        with respect to FIGS. 10-12.

The processor 330 may execute the frame formatting and exchange softwaremodule 342 to facilitate the creation and exchange of any suitableframes (such as data frames, action frames, control frames, andmanagement frames) between the AP 300 and other wireless devices. Theprocessor 330 may execute the frequency hopping pattern and schedulingSW module 343 to select a unique frequency hopping pattern for each of anumber of wireless devices that may qualify the wireless devices asfrequency hopping devices, and to determine or select a frequencyhopping schedule based on the unique frequency hopping patterns. Theprocessor 330 may execute the resource unit allocation software module344 to allocate unique sequences of RUs to the wireless devices (such asbased on frequency hopping schedules or unique frequency hoppingpatterns), for example, to allow the wireless devices to transmit ULOFDMA communications using frequency hopping techniques. The processor330 may execute the announcement software module 345 to announce orotherwise indicate the frequency hopping patterns, the frequency hoppingschedule, and the allocation of unique sequences of RUs to the wirelessdevices.

As mentioned above, the IEEE 802.11ax specification may introducemultiple access mechanisms, such as an orthogonal frequency-divisionmultiple access (OFDMA) mechanism, to allow multiple STAs to transmitand receive data on a shared wireless medium at the same time. For awireless network using OFDMA, the available frequency spectrum may bedivided into a plurality of resource units (RUs) each including a numberof different frequency subcarriers, and different RUs may be allocatedor assigned to different wireless devices (such as STAs) at a givenpoint in time. In this manner, multiple wireless devices mayconcurrently transmit data on the wireless medium using their assignedRUs or frequency subcarriers. Because each RU may include a subset ofthe available frequency subcarriers that is much smaller than theoverall frequency spectrum of the wireless medium, the IEEE 802.11axspecification may allow wireless devices to transmit data to each otherusing smaller channel bandwidths of 2 MHz, 4 MHz, 8 MHz, and 16 MHz(such as compared to a primary 20 MHz channel and one or more secondarychannels of varying bandwidths).

FIG. 4 shows an example subcarrier allocation diagram 400 for an 80 MHzchannel that may be used for narrowband transmissions. As used herein,the term “narrowband transmissions” may refer to transmissions usingfrequency bandwidths of less than 20 MHz. The wireless channel depictedin FIG. 4 may be divided into a number of resource units (RUs), and eachof the RUs may include a number of subcarriers. For example, a firstsubcarrier allocation 410 may include a number of resource unitsRU1-RU37 each including 26 subcarriers, a second subcarrier allocation420 may include a number of resource units RU1-RU16 each including 52subcarriers, a third subcarrier allocation 430 may include a number ofresource units RU1-RU8 each including 106 subcarriers, a fourthsubcarrier allocation 440 may include a number of resource units RU1-RU4each including 242 subcarriers, a fifth subcarrier allocation 450 mayinclude a number of resource units RU1-RU2 each including 484subcarriers, and a sixth subcarrier allocation 460 may include one RUincluding 996 subcarriers (with the left half of the channel forsingle-user (SU) operations). For each of the example subcarrierallocations 410, 420, 430, 440, 450, and 460 depicted in FIG. 4,adjacent RUs may be separated by a null subcarrier (such as a DCsubcarrier), for example, to reduce leakage between adjacent RUs. It isnoted that the numbers 26, 52, 106, 242, 484, and 996 in the examplesubcarrier allocation diagram 400 represent the number of frequencysubcarriers in each of the resource units for a corresponding subcarrierallocation.

An AP may allocate specific or dedicated RUs to a number of wirelessdevices using a trigger frame. In some implementations, the triggerframe may identify a number of STAs associated with the AP, and maysolicit uplink (UL) multi-user (MU) data transmissions from theidentified STAs using their allocated RUs. The trigger frame may useassociation identification (AID) values, assigned by the AP to itsassociated STAs, to identify which STAs are to transmit UL data to theAP in response to the trigger frame. In some aspects, the trigger framemay indicate the RU size and location, the modulation and coding scheme(MCS), and the power level for UL transmissions to be used by each ofthe STAs identified in the trigger frame. As used herein, the RU sizemay indicate the bandwidth of the RU, and the RU location may indicatewhich frequency subcarriers are allocated to the RU.

FIG. 5 shows a sequence diagram 500 depicting an example allocation ofresource units (RUs) for uplink (UL) transmissions. The AP of FIG. 5 maybe any suitable AP including, for example, the AP 110 of FIG. 1 or theAP 300 of FIG. 3. Each of the wireless stations STA1-STAn may be anysuitable wireless station including, for example, the stations STA1-STA4of FIG. 1 or the STA 200 of FIG. 2. In some implementations, the AP maycontend for medium access during a backoff period or a pointcoordination function (PCF) interframe space (PIFS) duration (such asbetween times t₁ and t₂). In other implementations, the AP may contendfor medium access using another suitable channel access mechanism. Insome other implementations, the AP may utilize a multiple channel accessmechanism, for example, and may not contend for medium access.

The AP gains access to the wireless medium at time t₂, and may transmita trigger frame 502 to the stations STA1-STAn on a downlink (DL) channelTime t₂ may indicate a beginning of a transmit opportunity (TXOP) 508.The trigger frame 502 may allocate a dedicated RU to each of a number ofthe stations STA1-STAn identified by the trigger frame 502, and maysolicit UL MU data transmissions from the identified stations STA1-STAn.In some aspects, the dedicated RUs allocated by the trigger frame 502may be unique, for example, so that the stations STA1-STAn may transmitUL data to the AP at the same time (or at substantially the same time).

The stations STA1-STAn may receive the trigger frame 502 at (or around)time t₃. Each of the identified stations STA1-STAn may decode thetrigger frame 502 to determine the size and location of the dedicated RUallocated by the trigger frame 502. In some aspects, the trigger frame502 may schedule UL data transmissions from the identified stationsSTA1-STAn to commence at an unspecified interframe spacing (xIFS)duration after reception of the trigger frame 502, for example, asdepicted in the example of FIG. 5.

At time t₄, the identified stations STA1-STAn may begin transmitting ULMU data 504 on their respective dedicated RUs. In some aspects, each ofthe identified stations STA1-STAn may determine whether the frequencyband associated with its allocated RU has been idle for a duration (suchas a PIFS duration) prior to transmitting UL MU data to the AP.

The AP may receive the UL MU data 504 from the identified stationsSTA1-STAn at time t₅, and may acknowledge reception of the UL MU data504 by transmitting a multi-station block acknowledgement (M-BA) frame506 to the stations STA1-STAn at time t₆. In some aspects, the AP maytransmit the M-BA frame 506 a short interframe spacing (SIFS) durationafter receiving the UL MU data 504 from the stations STA1-STAn. In otherimplementations, the AP may transmit the M-BA frame 506 after anothersuitable duration.

Wireless devices that transmit data using a relatively narrow bandwidthmay have a shorter range than wireless devices that transmit data usinga relatively wide bandwidth. In some aspects, narrowband communicationsmay refer to frequency ranges in which the frequency response of thechannel is relatively flat (such that the gain is relatively constantfor all frequencies), and wideband communications may refer to frequencyranges that are greater than narrowband communications (such that thefrequency response is not flat). A wideband wireless medium is typicallydivided into a primary channel and one or more secondary channels. Theprimary and secondary channels may be of various bandwidths, and may beformed by bonding a number of 20 MHz channels together to form 40 MHzchannels, 80 MHz channels, or 160 MHz channels. In some aspects, an 80MHz frequency spectrum may be divided into a primary 20 MHz channel, asecondary 20 MHz channel, and a secondary 40 MHz channel. In otheraspects, an 80 MHz frequency spectrum may be divided into a primary 40MHz channel and a secondary 40 MHz channel.

An AP operating in an OFDMA-based wireless network utilizing an 80 MHzfrequency spectrum may allocate RUs smaller than 20 MHz to wirelessdevices for UL transmissions. In some aspects, the AP may allocaterelatively small RUs having sizes such as 2 MHz, 4 MHz, 8 MHz, and 16MHz to wireless devices for UL transmissions. Because power spectraldensity limits imposed by governmental regulations are typicallyexpressed as a function of power versus frequency bandwidth,transmission power limits for a given RU are typically proportional tothe size of the RU. More specifically, governmental regulationstypically allow a wireless device to use higher power levels to transmitwireless signals on a relatively large RU (such as 20 MHz wide) than totransmit wireless signals on a relatively small RU (such as 2 MHz wide).

In some implementations, if a wireless device is allocated an RU havinga number (N_(RU)) of subcarriers in a wireless network utilizing an 80MHz channel having a total number (N_(tot)) of available subcarriers,then the power spectral density (PSD) gain (G_(PSD)) of the wirelessdevice when transmitting data using a smaller RU (as compared with theallocated RU) may be expressed as G_(PSD)=10 log 10(N_(tot)/N_(RU)). Forexample, the PSD gain of the wireless device for transmissions using a 2MHz RU may be expressed as G_(PSD)=10 log 10(37)=15.6 dB. Because a PSDgain of 15.6 dB exceeds the 11 dBm/MHz PSD limit imposed on Wi-Fidevices by the ETSI, the wireless device would need to reduce itstransmission power level to comply with the ETSI's PSD limits on Wi-Fidevices, which in turn may undesirably decrease the range of thewireless device.

In accordance with aspects of the present disclosure, a wireless devicemay employ frequency hopping techniques for OFDMA transmissions toqualify as a frequency hopping device. Because frequency hopping devicesare allowed higher transmit power levels than Wi-Fi devices for a giventransmission bandwidth, the ability to qualify as a frequency hoppingdevice may allow Wi-Fi devices to transmit OFDMA communications athigher power levels than would be possible without using frequencyhopping techniques. In some implementations, an AP may select a uniquefrequency hopping pattern for each of a number of selected wirelessdevices, for example, so that each of the selected wireless devices canqualify as a frequency hopping device. The AP may combine the variousunique frequency hopping patterns into a frequency hopping schedule, andallocate RUs to the selected wireless devices according to the frequencyhopping schedule. In some aspects, the AP may select a predefinedfrequency hopping pattern for each of the selected wireless devices. Inother aspects, the AP may select a proprietary frequency hopping patternfor each of the selected wireless devices.

The AP may announce the frequency hopping schedule and the allocated RUsto the selected wireless devices in any suitable manner In some aspects,the AP may announce the frequency hopping schedule and the allocated RUsto the selected wireless devices in one or more trigger frames. In otheraspects, the AP may announce the frequency hopping schedule to theselected wireless devices in a beacon frame, and may allocate RUs basedon the frequency hopping schedule to the selected wireless devices inone or more trigger frames. In still other aspects, the AP may announcethe frequency hopping schedule to the selected wireless devices usingany suitable broadcast or multicast frame or packet.

By qualifying each of the wireless devices as a frequency hopping device(rather than as a Wi-Fi device), aspects of the present disclosure mayallow the wireless devices to transmit wireless signals at power levelsgreater than the PSD limits imposed on OFDMA transmissions, which canincrease the range of the wireless devices. For example, by qualifying awireless device operating in Europe as a frequency hopping device, thewireless device may transmit OFDMA communications on a 2 MHz RU usingpower levels up to 20 dBm (such as compared to the ETSI's limit of 14dBm on OFDMA transmissions on a 2 MHz channel).

The AP may select or dynamically adjust the frequency hopping patternsbased on its geographic location, for example, so that the AP and theselected wireless devices can comply with applicable power spectraldensity limits for frequency hopping devices. For one example, Japanconsiders a wireless device to be a frequency hopping device in the 2.4GHz band if the wireless device hops over 15 or more channels and has adwell time in each of the channels that is less than 400 milliseconds(ms). For another example, Europe considers a wireless device to be afrequency hopping device in the 2.4 GHz band if the wireless device hopsover 15 or more channels and the accumulated dwell time in each channelis less than 15 ms over the frequency hopping duration.

In some implementations, the AP may select unique frequency hoppingpatterns that do not assign the same frequency subcarriers to the samewireless device for at least 15 successive transmissions. Morespecifically, the AP may determine a frequency hopping schedule andallocate unique sequences of RUs to its wireless devices so that each ofthe wireless devices hops over at least 15 different RUs (or channels),for example, to qualify the wireless devices as frequency hoppingdevices in Europe and Japan. In some aspects, the AP may selectfrequency hopping patterns to ensure that each wireless device spendsless than 400 ms transmitting data on a given RU, for example, toqualify as a frequency hopping device in Japan. In other aspects, the APmay select frequency hopping patterns to ensure that the accumulateddwell time for the wireless devices in each of the allocated RUs is lessthan 15 ms over the frequency hopping sequence, for example, to qualifyas frequency hopping devices in Europe.

FIG. 6A shows a sequence diagram 600A depicting an example allocation ofresource units (RUs) based on frequency hopping. For purposes ofdiscussion herein, FIG. 6A depicts an access point (AP) allocating RUsto a number of associated wireless stations STA1-STA4. The AP may be anysuitable AP including, for example, the AP 110 of FIG. 1 or the AP 300of FIG. 3. Each of the stations STA1-STA4 may be any suitable wirelessstation including, for example, the stations STA1-STA4 of FIG. 1 or theSTA 200 of FIG. 2.

The AP may select a unique frequency hopping pattern for each of itsassociated stations STA1-STA4, and may determine a frequency hoppingschedule for UL transmissions based on the selected frequency hoppingpatterns. In some aspects, the frequency hopping patterns selected bythe AP may be based on the geographic location of the AP. In otheraspects, the frequency hopping patterns selected by the AP also maydepend upon the available frequency spectrum, the number of availableRUs, and the number of subcarriers for each of the RUs.

In some implementations, the AP may contend for medium access during abackoff period or a PIFS duration (such as between times t₁ and t₂). Inother implementations, the AP may contend for medium access usinganother suitable channel access mechanism. In some otherimplementations, the AP may utilize a multiple channel access mechanism,for example, and may not contend for medium access.

The AP gains access to the wireless medium at time t₂, which may be thebeginning of a first TXOP 601. The AP may transmit a trigger frame 610to the stations STA1-STA4 on a DL channel In some implementations, thetrigger frame 610 may announce the frequency hopping schedule to thestations STA1-STA4, and may allocate a unique sequence of RUs to each ofthe stations STA1-STA4 based on the frequency hopping patterns selectedby the AP. In some aspects, the trigger frame 610 may indicate the RUsizes and locations, the MCSs, and the power levels to be used by eachof the stations STA1-STA4 for UL transmissions using the allocated RUs.

As depicted in FIG. 6A, the trigger frame 610 allocates unique sequencesof RUs for which each of the stations STA1-STA4 is to use for frequencyhopping during a sequence period. The sequence period may include or bedefined by the number of different RUs between which a wireless devicemust hop to qualify as a frequency hopping device. For example, if theAP is located where governmental regulations define a frequency hoppingdevice as a device that hops over 15 different channels, then thesequence period may correspond to the period of time during which thestations STA1-STA4 hop between 15 different RUs.

In some implementations, the trigger frame 610 may indicate that theallocation of RUs is based on a frequency hopping schedule, and mayindicate that the AP is instructing its associated devices to employfrequency hopping techniques for UL OFDMA transmissions. In someaspects, the RUs allocated to the stations STA1-STA4 of FIG. 6A may beof different sizes. For example, stations that have a relatively smallamount of UL data may be allocated relatively small RUs (such as 2 MHz),and stations that have a relatively large amount of UL data may beallocated relatively large RUs (such as 4 MHz, 8 MHz, or 16 MHz).

The stations STA1-STA4 may receive the trigger frame 610 at (or around)time t₃. Upon receiving the trigger frame 610, each of the stationsSTA1-STA4 may extract the frequency hopping schedule and may determineits unique sequence of RUs allocated by the AP. In some aspects, thefrequency hopping schedule may instruct each of the stations STA1-STA4to dwell less than a duration on each of the allocated RUs (such as forless than 400 ms per RU when the AP is located in Japan). In otheraspects, the frequency hopping schedule may instruct each of thestations STA1-STA4 that the accumulated dwell time is to be less than 15ms over the sequence period (such as when the AP is operating inEurope).

At time t₄, each of the stations STA1-STA4 may begin transmitting UL MUdata 612 on its unique RU. For the example of FIG. 6A, the first stationSTA1 transmits UL MU data 612 on resource unit RU1, the second stationSTA2 transmits UL MU data 612 on resource unit RU16, the third stationSTA3 transmits UL MU data 612 on resource unit RU21, and the fourthstation STA4 transmits UL MU data 612 on resource unit RU26. In thismanner, each of the stations STA1-STA4 may transmit UL MU data to the APat the same time (or substantially the same time) using different RUs.

The trigger frame 610 may solicit UL data transmissions from thestations STA1-STA4 to commence at an unspecified interframe spacing(xIFS) duration after reception of the trigger frame 610. In someaspects, the trigger frame 610 may include a channel sense (CS) bitindicating whether the stations STA1-STA4 should sense the channel priorto transmitting UL MU data. For one example, if the CS bit is asserted,then each of the stations STA1-STA4 may determine whether the frequencyband of its allocated RU has been idle for a duration (such as a PIFSduration) prior to transmitting UL MU data to the AP. For anotherexample, if the CS bit is not asserted, then the stations STA1-STA4 maycommence UL transmissions upon expiration of the xIFS duration.

The AP may receive the UL MU data 612 from the stations STA1-STA4 attime t₅, and may acknowledge reception of the UL MU data 612 bytransmitting a multi-station block acknowledgement (M-BA) frame 616 tothe stations STA1-STA4 at time t₆. In some aspects, the AP may transmitthe M-BA frame 616 a short interframe spacing (SIFS) duration afterreceiving the UL MU data from the stations STA1-STA4. In otherimplementations, the AP may transmit the M-BA frame 616 after anothersuitable duration. The stations STA1-STA4 receive the M-BA frame 616 attime t₇, which may signal the end of the first TXOP 601.

After a duration, the AP may transmit a second trigger frame 620 to thestations STA1-STA4. The second trigger frame 620, which may signal abeginning of a second TXOP 602, may solicit UL transmissions from thestations STA1-STA4 on their allocated RUs. For the example of FIG. 6A,the first station STA1 transmits UL MU data 622 on resource unit RU2,the second station STA2 transmits UL MU data 622 on resource unit RU17,the third station STA3 transmits UL MU data 622 on resource unit RU22,and the fourth station STA4 transmits UL MU data 622 on resource unitRU27. Because the first trigger frame 610 has already informed thestations STA1-STA4 of the frequency hopping schedule and has alreadyallocated unique sequences of RUs to each of the stations STA1-STA4 forthe sequence period, the second trigger frame 620 may not contain thefrequency hopping schedule and may not allocate RUs to the stationsSTA1-STA4 (such as to minimize the size and transmit duration of thesecond trigger frame 620).

The AP may acknowledge reception of the UL MU data 622 by transmitting asecond M-BA frame 626 to the stations STA1-STA4. Reception of the secondM-BA frame 626 by the stations STA1-STA4 may signal the end of thesecond TXOP 602. The stations STA1-STA4 may continue transmitting UL MUdata to the AP in this manner, for example, such that (1) during anygiven TXOP each of the stations STA1-STA4 is allocated a different RUand (2) each of the stations STA1-STA4 does not transmit UL data on thesame RU in any given sequence period (such as 15 TXOPs).

FIG. 6B shows a sequence diagram 600B depicting another exampleallocation of resource units (RUs) based on frequency hopping. Thesequence diagram 600B of FIG. 6B is similar to the sequence diagram 600Aof FIG. 6A, except that instead of transmitting a trigger frame thatannounces the frequency hopping schedule and that allocates uniquesequences of RUs for the entire sequence period, the AP transmits atrigger frame 611, at time t₂, that allocates RUs to the stationsSTA1-STA4 for the corresponding TXOP 601. Each of the stations STA1-STA4receives the trigger frame 611, identifies its allocated RU, and thentransmits UL MU data to the AP using its allocated RU. After the firstTXOP 601 ends, the AP transmits a second trigger frame 621 thatallocates RUs to the stations STA1-STA4 for the second TXOP 602. Each ofthe stations STA1-STA4 receives the second trigger frame 621, identifiesits allocated RU, and then transmits UL MU data to the AP using itsallocated RU. The stations STA1-STA4 may continue transmitting UL MUdata to the AP in this manner, for example, such that (1) at thebeginning of each TXOP the AP transmits a trigger frame to allocateunique RUs to the stations STA1-STA4, and (2) each of the stationsSTA1-STA4 does not transmit UL data on the same RU in any given sequenceperiod (such as 15 TXOPs).

FIG. 7A shows an illustration 700 depicting example sequences of RUsthat may be used for frequency hopping during OFDMA transmissions. Forpurposes of discussed herein, the unique RU sequences 701-704 depictedin the illustration 700 may be used by respective stations STA1-STA4 ofFIGS. 6A and 6B for transmitting UL data. It is to be understood thatthe unique RU sequences 701-704 may be used by other wireless devices toqualify as frequency hopping devices during OFDMA transmissions, andthat the stations STA1-STA4 of FIGS. 6A and 6B may use other suitablesequences of RUs to qualify as frequency hopping devices during OFDMAtransmissions.

Each of the unique RU sequences 701-704 is shown to include 15 differentRUs that may be used by a respective one of the stations STA1-STA4 totransmit UL data using OFDMA communications during a sequence period710. Although the unique RU sequences 701-704 may include some of thesame RUs, each of the unique RU sequences 701-704 includes only oneinstance of any given RU, and the same RU is not allocated to more thanone of the unique RU sequences 701-704 at the same time.

In some implementations, the RUs within the unique RU sequences 701-704may each be allocated to a corresponding station for a duration equal to(or substantially equal to) the channel dwell time specified forfrequency hopping devices. For example, when the AP is located in Japan,each of the RUs within a given one of the unique RU sequences 701-704may be allocated to a corresponding station for no more than 400 ms. Inother implementations, the accumulated dwell time in each RU is lessthan an amount over the duration of the sequence period 710. Forexample, when the AP is located in Europe, the accumulated dwell time ineach RU is less than 15 ms over the duration of the sequence period 710.

In addition, or in the alternative, each of the RUs within a given oneof the unique RU sequences 701-704 may correspond to a TXOP. For theexample of FIG. 7A, the first station STA1 may transmit UL data usingRU1 during a first TXOP, may transmit UL data using RU2 during a secondTXOP, may transmit UL data using RU3 during a third TXOP, and so on, andthen transmit UL data using RU15 during a fifteenth TXOP. The secondstation STA2 may transmit UL data using RU16 during the first TXOP, maytransmit UL data using RU17 during the second TXOP, may transmit UL datausing RU18 during the third TXOP, and so on, and then transmit UL datausing RU10 during the fifteenth TXOP. The third station STA3 maytransmit UL data using RU21 during the first TXOP, may transmit UL datausing RU22 during the second TXOP, may transmit UL data using RU23during the third TXOP, and so on, and then transmit UL data using RU5during the fifteenth TXOP. The fourth station STA4 may transmit UL datausing RU26 during the first TXOP, may transmit UL data using RU27 duringthe second TXOP, may transmit UL data using RU28 during the third TXOP,and so on, and then transmit UL data using RU20 during the fifteenthTXOP.

By using the unique RU sequences 701-704 to frequency hop during OFDMAtransmissions, each of the stations STA1-STA4 may qualify as a frequencyhopping device, and thus use transmission power levels imposed onfrequency hopping devices. Because many governmental regulations allowhigher transmission power levels for frequency hopping devices than forwireless devices using OFDMA communications, the ability to qualify asfrequency hopping devices may allow the stations STA1-STA4 to increasetheir transmission power levels without violating PSD limits. Forexample, if the stations STA1-STA4 are operating in a wireless networklocated in Europe, the ability to qualify as frequency hopping devicesmay allow the stations STA1-STA4 to increase their transmission powerlevels from approximately 14 dBm (such as imposed on wireless devicesusing OFDMA transmissions) to approximately 20 dBm (such as imposed onfrequency hopping devices). In this manner, aspects of the presentdisclosure may increase the wireless range of the stations STA1-STA4without violating power spectral density limits.

FIG. 7B shows an illustrative table 720 depicting an exampleconstruction of the unique RU sequence 701 of FIG. 7A. The exampleconstruction of the unique RU sequence 701 is described below in thecontext of an 80 MHz Wi-Fi network. It is to be understood that theexample construction of the unique RU sequence 701, or derivationsthereof, also may be applicable to wireless networks utilizing otherfrequency bandwidths (such as a 40 MHz bandwidth).

Referring also to FIG. 4, the IEEE 802.11ax specification may specifythat an 80 MHz channel includes thirty-seven (37) 2 MHz RUs. In someimplementations, an AP may assign each of the thirty-seven RUs (denotedas RU1-RU37 in FIG. 7B) an initial count value of “0.” An RU having acount value of “0” may be available for allocation to one of the AP'sassociated devices for UL OFDMA transmissions during a next TXOP.

When the AP initially allocates an RU to a wireless device for UL OFDMAtransmissions, the AP may reset the count value of the RU to a maximumcount value of “15.” For each subsequent TXOP, the AP may select one ofthe RUs that has a count value of “0,” and may decrement the countvalues of all RUs previously allocated to the wireless device by a valueof “1.” This process of allocating unique RUs to the wireless device maycontinue until the wireless device has transmitted UL MU data on atleast 15 different RUs (which may correspond to a sequence period forthe wireless device). A similar process may be performed for each of thewireless devices identified for UL transmissions by the trigger frame.In this manner, the AP may ensure that none of its wireless devicestransmits UL data on the same RU for at least 15 TXOPs.

In some aspects, the maximum count value may be based on the number ofsuccessive channel hops for which a wireless device can qualify as afrequency hopping device. Thus, in locations such as Japan and Europe,when an RU is initially allocated to a wireless device for UL OFDMAtransmissions, the AP may reset its count value to a maximum count valueof “15,” for example, because both Japan and Europe consider a wirelessdevice to be a frequency hopping device based at least in part on thewireless device hopping between 15 different channels (or RUs) within agiven sequence period. For other locations, the maximum count value maybe set to another suitable number depending, for example, on applicablegovernmental regulations for qualifying a wireless device as a frequencyhopping device.

For the example of FIG. 7B, the AP allocates RU1 to STA1 during thefirst TXOP, and resets the count value of RU1 to 15. For the secondTXOP, the AP allocates RU2 to STA1, resets the count value of RU2 to 15,and decrements the count value of RU1 to 14. For the third TXOP, the APallocates RU3 to STA1, resets the count value of RU3 to 15, decrementsthe count value of RU2 to 14, and decrements the count value of RU1 to13. For the fourth TXOP, the AP allocates RU4 to STA1, resets the countvalue of RU4 to 15, decrements the count value of RU3 to 14, decrementsthe count value of RU2 to 13, and decrements the count value of RU1 to12. This process may continue until the AP has allocated 15 differentRUs to STA1, for example, during a sequence period that spans 15 RUs.Thus, for the fifteenth TXOP, the AP may allocate RU15 to STA1, resetits count value to 15, and decrement each of the count values of thepreviously allocated resource units RU1-RU14 by 1, for example, asdepicted in the table 720 of FIG. 7B.

The AP may construct unique RU sequences for other wireless devices in asimilar manner, for example, by staggering the allocation of RUs in amanner that prevents the same RU from being used by more than onewireless device in a given TXOP. For example, the AP may use the exampletable 720 to construct unique RU sequences 702-704 for respectivestations STA2-STA4 of FIG. 7A.

In other implementations, the AP may use negative numbers (rather thanpositive numbers) to determine when previously used RUs may again beavailable for allocation to wireless devices. For example, when the APallocates an RU to a wireless device during a TXOP, the AP may reset thecount value of the RU to a minimum weight value of “−15” (or othernumber based on the number of successive channel hops for a wirelessdevice to qualify as a frequency hopping device). Then, the AP mayincrement the count value for previously allocated RUs by “1” (such asto a more positive number) during each subsequent TXOP. When the countvalue for a given RU has been incremented to its initial count value of“0,” the given RU may once again be allocated by the AP to one of itswireless devices for UL OFDMA transmissions.

FIG. 8 shows an example trigger frame 800. The trigger frame 800 may beused as the trigger frame 610 of FIG. 6A or as the trigger frame 620 ofFIG. 6B. The trigger frame 800 is shown to include a frame control field801, a duration field 802, a receiver address (RA) field 803, atransmitter address (TA) field 804, a Common Info field 805, a number ofPer User Info fields 806(1)-806(n), and a frame check sequence (FCS)field 807.

The frame control field 801 includes a Type field 801A and a Sub-typefield 801B. The Type field 801A may store a value to indicate that thetrigger frame 800 is a control frame, and the Sub-type field 801B maystore a value indicating a type of the trigger frame 800. The durationfield 802 may store information indicating a duration or length of thetrigger frame 800. The RA field 803 may store the address of a receivingdevice (such as one of the wireless stations STA1-STA4 of FIGS. 6A and6B). The TA field 804 may store the address of a transmitting device(such as the AP of FIGS. 6A and 6B). The Common Info field 805 may storeinformation common to one or more receiving devices. Each of the PerUser Info fields 806(1)-806(n) may store information for a particularreceiving device, as described in more detail below with respect to FIG.9B. The FCS field 807 may store a frame check sequence (such as forerror detection). In some implementations, the Common Info field 805 maystore a frequency hopping schedule. In other implementations, thefrequency hopping schedule may be stored in an information element (IE)or a vendor-specific information element (VSIE) included within orappended to the trigger frame 800 (the IE and VSIE not shown forsimplicity). In some other implementations, the frequency hoppingschedule may be stored in a packet extension appended to the triggerframe 800 (the packet extension not shown for simplicity).

FIG. 9A shows an example Common Info field 900. The Common Info field900 may be one implementation of the Common Info field 805 of thetrigger frame 800 of FIG. 8. The Common Info field 900 is shown toinclude a length subfield 901, a cascade indication subfield 902, ahigh-efficiency signaling A (HE-SIG-A) info subfield 903, a cyclicprefix (CP) and legacy training field (LTF) type subfield 904, a triggertype subfield 905, and a trigger-dependent common info subfield 906. Thelength subfield 901 may indicate the length of a legacy signaling fieldof the UL data frames to be transmitted in response to the trigger frame800. The cascade indication subfield 902 may indicate whether asubsequent trigger frame follows the current trigger frame. For example,the cascade indication subfield 902 of the trigger frame 611 of FIG. 6Bmay indicate that trigger frame 621 is to follow the trigger frame 611.

The HE-SIG-A Info subfield 903 may indicate the contents of a HE-SIG-Afield of the UL data frames to be transmitted in response to the triggerframe 800. The CP and LTF type subfield 904 may indicate the cyclicprefix and HE-LTF type of the UL data frames to be transmitted inresponse to the trigger frame 600. The trigger type subfield 905 mayindicate the type of trigger frame. The trigger-dependent common infosubfield 906 may indicate trigger-dependent information. In someaspects, the trigger-dependent common info subfield 906 may store afrequency hopping schedule.

FIG. 9B shows an example Per User Info field 910. The Per User Infofield 910 may be one implementation of the Per User Info fields806(1)-806(n) of the trigger frame 800 of FIG. 8. The Per User Infofield 910 is shown to include a User Identifier subfield 911, an RUAllocation subfield 912, a Coding Type subfield 913, an MCS subfield914, a dual-carrier modulation (DCM) subfield 915, a spatial stream (SS)Allocation subfield 916, and a trigger-dependent Per User info subfield917. The User Identifier subfield 911 may indicate the associationidentification (AID) of the STA to which a dedicated RU is allocated fortransmitting UL MU data. The RU Allocation subfield 912 may identify thededicated RU allocated to the corresponding STA (such as the STAidentified by the User Identifier subfield 911). The Coding Typesubfield 913 may indicate the type of coding to be used by thecorresponding STA when transmitting UL data using the allocated RU. TheMCS subfield 914 may indicate the MCS to be used by the correspondingSTA when transmitting UL data using the allocated RU. The DCM subfield915 may indicate the dual carrier modulation to be used by thecorresponding STA when transmitting UL data using the allocated RU. TheSS Allocation subfield 916 may indicate the number of spatial streams tobe used by the corresponding STA when transmitting UL data using theallocated RU.

The trigger-dependent Per User info subfield 917 may store information,for the STA identified by User Identifier subfield 911, that dependsupon the type of trigger frame. For example, if the trigger frame is amulti-user block acknowledgement request (MU-BAR) frame, then thetrigger-dependent Per User info subfield 917 may store BAR controlparameters and BAR information. In some aspects, the trigger-dependentPer User info subfield 917 may store a frequency hopping pattern for acorresponding STA.

FIG. 10 shows an illustrative flow chart depicting an example operation1000 for qualifying a wireless device as a frequency hopping device.Although the example operation 1000 is described below in the context ofan AP allocating resource units to a wireless device, it is to beunderstood that any suitable wireless device may perform the operation1000 of FIG. 10. For some implementations, the wireless device may be anexample of one of the stations STA1-STA4 of FIG. 1 or the STA 200 ofFIG. 2, and the AP may be an example of the AP 110 of FIG. 1 or the AP300 of FIG. 3.

The AP may determine a frequency hopping pattern for the wireless device(1002). In some implementations, the frequency hopping pattern may bebased on governmental regulations indicating qualifications to beconsidered as a frequency hopping device. In some aspects, the frequencyhopping pattern may indicate that the wireless device is to hop between15 or more unique frequency bands during a time period. The frequencyhopping pattern also may indicate a maximum dwell time on each of theunique frequency bands or may indicate that an accumulated dwell time inthe unique frequency bands is to be no more than a time period greaterthan a duration of the frequency hopping sequence.

The AP may announce the frequency hopping pattern to the wireless device(1004). In some implementations, the AP may announce the frequencyhopping pattern in a beacon frame. The beacon frame also may include afrequency hopping schedule for a number of wireless devices associatedwith the AP. In some aspects, the frequency hopping schedule may includeor be formed by the frequency hopping patterns of the number of wirelessdevices associated with the AP. In other implementations, the AP mayannounce the frequency hopping pattern in a trigger frame. The triggerframe also may include the frequency hopping schedule for multiplewireless devices associated with the AP.

The AP may allocate a sequence of unique resource units to the wirelessdevice based on the frequency hopping pattern (1006). Each of the uniqueresource units includes a different set of frequency subcarriers, forexample, so that multiple wireless devices can transmit uplink data atthe same time. In some aspects, each of the unique resource units may beassociated with a corresponding one of a series of transmitopportunities (TXOPs).

In some implementations, the trigger frame may allocate the sequence ofunique resource units to the wireless device (1006A). The trigger framemay contain an indication that the wireless device is to successivelyfrequency hop between more than a specified number of the uniqueresource units. In addition, or in the alternative, the trigger framemay contain one of an indication that the wireless device is to dwell oneach of the unique resource units for less than a duration and anindication that an accumulated dwell time in the unique resource unitsis to be no more than a time period greater than a duration of thesequence of unique resource units. In some aspects, the dwell time is400 milliseconds, the time period is 15 milliseconds, and the sequenceincludes at least 15 unique resource units.

In other implementations, each trigger frame may allocate resource unitsto the wireless device for a corresponding TXOP, for example, asdescribed above with respect to FIG. 6B.

The AP may receive, from the wireless device, a series of uplinkorthogonal frequency-division multiple access (OFDMA) transmissions onthe allocated sequence of unique resource units during a sequence period(1008). Because the wireless device switches or “hops” between differentresource units while sending a series of OFDMA transmissions to the APin a manner consistent with frequency hopping devices, the wirelessdevice may qualify as a frequency hopping device and transmit signals athigher power levels associated with frequency hopping devices. In thismanner, aspects of the present disclosure may increase the range of thewireless device.

FIG. 11 shows an illustrative flow chart depicting an example operation1100 for allocating resource units to a wireless device. Although theexample operation 1100 is described below in the context of an APallocating resource units to a wireless device, it is to be understoodthat any suitable wireless device may perform the operation 1100 of FIG.11. For some implementations, the wireless device may be an example ofthe stations STA1-STA4 of FIG. 1 or the STA 200 of FIG. 2, and the APmay be an example of the AP 110 of FIG. 1 or the AP 300 of FIG. 3.

The AP may assign, to each of a plurality of resource units, a countvalue equal to zero (1102). For example, referring also to FIG. 7B, theAP may assign each of the resource units RU1-RU37 an initial count valueof “0.” A resource unit (RU) having a count value of “0” may beavailable for allocation to one of the AP's associated devices for ULOFDMA transmissions during a next TXOP.

The AP may allocate a first of the plurality of resource units to thewireless device for a first transmit opportunity (TXOP) (1104), and thenreset the count value of the first resource unit to a maximum valuebased on its allocation to the wireless device (1106). In someimplementations, the maximum count value may be “15,” for example,because both Japan and Europe consider a wireless device to be afrequency hopping device based at least in part on the wireless devicehopping between 15 different channels (or RUs) within a given sequenceperiod.

The AP may decrement the count value of the first resource unit by oneduring a next TXOP (1108). In implementations for which the maximumcount value is “15,” the AP may decrement the count value of the firstresource unit by one to “14.” This process may continue until thewireless device has transmitted UL MU data on at least 15 different RUs,after which the count value of the first resource unit will return tozero. Thereafter, the AP may again allocate the first resource unit tothe wireless device.

FIG. 12 shows an illustrative flow chart depicting an example operation1200 for a wireless station transmitting data using resource unitsallocated based on a frequency hopping schedule. For someimplementations, the wireless station may be an example of one of thestations STA1-STA4 of FIG. 1 or the STA 200 of FIG. 2.

The wireless station may receive a frequency hopping pattern (1202), andmay receive an allocation of a sequence of unique resource units basedon the frequency hopping pattern, each of the unique resource unitsincluding a different set of frequency subcarriers (1204). The frequencyhopping pattern may be based on governmental regulations indicatingqualifications for a wireless station to be considered as a frequencyhopping device. In some aspects, the frequency hopping pattern mayindicate that the wireless station is to hop between 15 or more uniquefrequency bands during a time period. The frequency hopping pattern alsomay indicate a maximum dwell time on each of the unique frequency bandsor may indicate that an accumulated dwell time in the unique frequencybands is to be no more than a time period greater than a duration of thefrequency hopping sequence.

In some implementations, the wireless station may receive, from anaccess point (AP), a trigger frame that allocates the sequence of uniqueresource units to the wireless station and indicates that the wirelessstation is to successively frequency hop between more than a specifiednumber of the unique resource units. In some aspects, the trigger framealso may include the frequency hopping pattern. In other aspects, thefrequency hopping pattern may be broadcast in a beacon frame.

In addition, or in the alternative, the trigger frame may contain one ofan indication that the wireless station is to dwell on each of theunique resource units for less than a duration and an indication that anaccumulated dwell time in the unique resource units is to be no morethan a time period greater than a duration of the sequence of uniqueresource units. In some aspects, the dwell time is 400 milliseconds, thetime period is 15 milliseconds, and the sequence includes at least 15unique resource units.

The wireless station may transmit a series of orthogonalfrequency-division multiple access (OFDMA) data transmissions on theallocated sequence of unique resource units during a sequence period(1206). Each of the unique resource units may include a different set offrequency subcarriers, for example, so that multiple wireless stationscan transmit uplink data at the same time. In some aspects, each of theunique resource units may be associated with a corresponding one of aseries of transmit opportunities (TXOPs). Because the wireless stationswitches or “hops” between different resource units while sending aseries of OFDMA data transmissions (such as to the AP) in a mannerconsistent with frequency hopping devices, the wireless station mayqualify as a frequency hopping device and transmit signals at higherpower levels associated with frequency hopping devices. In this manner,aspects of the present disclosure may increase the range of the wirelessstation.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c.

The various illustrative logics, logical blocks, modules, circuits andalgorithm processes described in connection with the implementationsdisclosed herein may be implemented as electronic hardware, computersoftware, or combinations of both. The interchangeability of hardwareand software has been described generally, in terms of functionality,and illustrated in the various illustrative components, blocks, modules,circuits and processes described above. Whether such functionality isimplemented in hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

The hardware and data processing apparatus used to implement the variousillustrative logics, logical blocks, modules and circuits described inconnection with the aspects disclosed herein may be implemented orperformed with a general purpose single- or multi-chip processor, adigital signal processor (DSP), an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, or any combination thereof designed to perform thefunctions described herein. A general purpose processor may be amicroprocessor, or, any conventional processor, controller,microcontroller, or state machine. A processor also may be implementedas a combination of computing devices such as, for example, acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration. In some implementations,particular processes and methods may be performed by circuitry that isspecific to a given function.

In one or more aspects, the functions described may be implemented inhardware, digital electronic circuitry, computer software, firmware,including the structures disclosed in this specification and theirstructural equivalents thereof, or in any combination thereof.Implementations of the subject matter described in this specificationalso can be implemented as one or more computer programs, i.e., one ormore modules of computer program instructions, encoded on a computerstorage media for execution by, or to control the operation of, dataprocessing apparatus.

If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. The processes of a method or algorithmdisclosed herein may be implemented in a processor-executable softwaremodule which may reside on a computer-readable medium. Computer-readablemedia includes both computer storage media and communication mediaincluding any medium that can be enabled to transfer a computer programfrom one place to another. A storage media may be any available mediathat may be accessed by a computer. By way of example, and notlimitation, such computer-readable media may include RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that may be used to storedesired program code in the form of instructions or data structures andthat may be accessed by a computer. Also, any connection can be properlytermed a computer-readable medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk, and blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media. Additionally, the operations of a method oralgorithm may reside as one or any combination or set of codes andinstructions on a machine readable medium and computer-readable medium,which may be incorporated into a computer program product.

Various modifications to the implementations described in thisdisclosure may be readily apparent to those skilled in the art, and thegeneric principles defined herein may be applied to otherimplementations without departing from the spirit or scope of thisdisclosure. Thus, the claims are not intended to be limited to theimplementations shown herein, but are to be accorded the widest scopeconsistent with this disclosure, the principles and the novel featuresdisclosed herein.

What is claimed is:
 1. A method for qualifying a wireless device asfrequency hopping device, comprising: determining a frequency hoppingpattern for the wireless device; allocating a sequence of uniqueresource units to the wireless device based on the frequency hoppingpattern, each of the unique resource units including a different set offrequency subcarriers; and receiving, from the wireless device, a seriesof uplink orthogonal frequency-division multiple access (OFDMA)transmissions on the allocated sequence of unique resource units duringa sequence period.
 2. The method of claim 1, wherein the allocatingcauses the wireless device to frequency hop between the unique resourceunits for at least the sequence period.
 3. The method of claim 1,wherein each of the unique resource units is associated with acorresponding one of a series of transmit opportunities (TXOPs).
 4. Themethod of claim 1, further comprising: transmitting, to the wirelessdevice, a trigger frame that allocates the sequence of unique resourceunits to the wireless device and indicates that the wireless device isto successively frequency hop between more than a specified number ofthe unique resource units.
 5. The method of claim 4, wherein the triggerframe contains one of an indication that the wireless device is to dwellon each of the unique resource units for less than a duration and anindication that an accumulated dwell time in the unique resource unitsis to be no more than a time period greater than a duration of thesequence of unique resource units.
 6. The method of claim 5, wherein thedwell time is 400 milliseconds, the time period is 15 milliseconds, andthe sequence includes at least 15 unique resource units.
 7. The methodof claim 4, wherein the trigger frame contains a frequency hoppingschedule indicating a unique frequency hopping pattern for each of aplurality of wireless devices to transmit uplink data using OFDMAcommunications.
 8. The method of claim 1, wherein the allocatingcomprises: assigning, to each of a plurality of resource units, a countvalue equal to zero; allocating a first of the plurality of resourceunits to the wireless device for a first transmit opportunity (TXOP);resetting the count value of the first resource unit to a maximum valuebased on its allocation to the wireless device; and decrementing thecount value of the first resource unit by one during a next TXOP.
 9. Themethod of claim 8, wherein the maximum value of the count value is basedon a number of successive frequency hops associated with qualifying thewireless device as a frequency hopping device.
 10. An access point (AP),comprising: one or more processors; and a memory storing instructionsthat, when executed by the one or more processors, cause the AP toqualify a wireless device as frequency hopping device by: determining afrequency hopping pattern for the wireless device; allocating a sequenceof unique resource units to the wireless device based on the frequencyhopping pattern, each of the unique resource units including a differentset of frequency subcarriers; and receiving, from the wireless device, aseries of uplink orthogonal frequency-division multiple access (OFDMA)transmissions on the allocated sequence of unique resource units duringa sequence period.
 11. The AP of claim 10, wherein the allocating causesthe wireless device to frequency hop between the unique resource unitsfor at least the sequence period.
 12. The AP of claim 10, wherein eachof the unique resource units is associated with a corresponding one of aseries of transmit opportunities (TXOPs).
 13. The AP of claim 10,wherein execution of the instructions causes the AP to further:transmit, to the wireless device, a trigger frame that allocates thesequence of unique resource units to the wireless device and indicatesthat the wireless device is to successively frequency hop between morethan a specified number of the unique resource units.
 14. The AP ofclaim 13, wherein the trigger frame contains one of an indication thatthe wireless device is to dwell on each of the unique resource units forless than a duration and an indication that an accumulated dwell time inthe unique resource units is to be no more than a time period greaterthan a duration of the sequence of unique resource units.
 15. The AP ofclaim 14, wherein the dwell time is 400 milliseconds, the time period is15 milliseconds, and the sequence includes at least 15 unique resourceunits.
 16. The AP of claim 13, wherein the trigger frame contains afrequency hopping schedule indicating a unique frequency hopping patternfor each of a plurality of wireless devices to transmit uplink datausing OFDMA communications.
 17. The AP of claim 10, wherein execution ofthe instructions for allocating the sequence of unique resource unitscauses the AP to: assign, to each of a plurality of resource units, acount value equal to zero; allocate a first of the plurality of resourceunits to the wireless device for a first transmit opportunity (TXOP);reset the count value of the first resource unit to a maximum valuebased on its allocation to the wireless device; and decrement the countvalue of the first resource unit by one during a next TXOP.
 18. Anon-transitory computer-readable medium comprising instructions that,when executed by one or more processors of an access point (AP), causethe AP to perform operations comprising: determining a frequency hoppingpattern for a wireless device; allocating a sequence of unique resourceunits to the wireless device based on the frequency hopping pattern,each of the unique resource units including a different set of frequencysubcarriers; and receiving, from the wireless device, a series of uplinkorthogonal frequency-division multiple access (OFDMA) transmissions onthe allocated sequence of unique resource units during a sequenceperiod.
 19. The non-transitory computer-readable medium of claim 18,wherein the allocating causes the wireless device to frequency hopbetween the unique resource units for at least the sequence period. 20.The non-transitory computer-readable medium of claim 18, whereinexecution of the instructions causes the AP to perform operationsfurther comprising: transmitting, to the wireless device, a triggerframe that allocates the sequence of unique resource units to thewireless device and indicates that the wireless device is tosuccessively frequency hop between more than a specified number of theunique resource units.
 21. The non-transitory computer-readable mediumof claim 20, wherein the trigger frame contains one of an indicationthat the wireless device is to dwell on each of the unique resourceunits for less than a duration and an indication that an accumulateddwell time in the unique resource units is to be no more than a timeperiod greater than a duration of the sequence of unique resource units.22. The non-transitory computer-readable medium of claim 21, wherein thedwell time is 400 milliseconds, the time period is 15 milliseconds, andthe sequence includes at least 15 unique resource units.
 23. Thenon-transitory computer-readable medium of claim 20, wherein the triggerframe contains a frequency hopping schedule indicating a uniquefrequency hopping pattern for each of a plurality of wireless devices totransmit uplink data using OFDMA communications.
 24. The non-transitorycomputer-readable medium of claim 18, wherein execution of theinstructions for allocating the sequence of unique resource units causesthe AP to perform operations further comprising: assigning, to each of aplurality of resource units, a count value equal to zero; allocating afirst of the plurality of resource units to the wireless device for afirst transmit opportunity (TXOP); resetting the count value of thefirst resource unit to a maximum value based on its allocation to thewireless device; and decrementing the count value of the first resourceunit by one during a next TXOP.
 25. A wireless station, comprising: oneor more processors; and a memory storing instructions that, whenexecuted by the one or more processors, cause the wireless station toqualify as a frequency hopping device by: receiving a frequency hoppingpattern; receiving an allocation of a sequence of unique resource unitsbased on the frequency hopping pattern, each of the unique resourceunits including a different set of frequency subcarriers; andtransmitting a series of orthogonal frequency-division multiple access(OFDMA) data transmissions on the allocated sequence of unique resourceunits during a sequence period.
 26. The wireless station of claim 25,wherein execution of the instructions causes the wireless station tofurther: receive a trigger frame that allocates the sequence of uniqueresource units to the wireless station and indicates that the wirelessstation is to successively frequency hop between more than a specifiednumber of the unique resource units.
 27. The wireless station of claim26, wherein the trigger frame contains one of an indication that thewireless station is to dwell on each of the unique resource units forless than a duration and an indication that an accumulated dwell time inthe unique resource units is to be no more than a time period greaterthan a duration of the sequence of unique resource units.
 28. Thewireless station of claim 27, wherein the dwell time is 400milliseconds, the time period is 15 milliseconds, and the sequenceincludes at least 15 unique resource units.
 29. The wireless station ofclaim 26, wherein the trigger frame contains a frequency hoppingschedule indicating a unique frequency hopping pattern for each of aplurality of wireless devices to transmit uplink data using OFDMAcommunications.
 30. The wireless station of claim 25, wherein each ofthe unique resource units is associated with a corresponding one of aseries of transmit opportunities (TXOPs).